First of all: I love the book.
But I have a slight suggestion:
It would be nice to have "before/after" branching in the github repo, so one would be able to follow along the coding process without recreating the basic structure of the code.
I really miss this in Chapter 7.

Currently some of the repos are a bit more messy than others because of changes to the code (and having the branch structure is more work and we don't want to redo it with every change).

So, bottom line, we have something in place for you and we're open to all suggestions to make it more accessible. Using branches for starting points and intermediate results is not really self-explanatory, so there will be an appendix on how we thought it should work.

Currently some of the repos are a bit more messy than others because of changes to the code (and having the branch structure is more work and we don't want to redo it with every change).

So, bottom line, we have something in place for you and we're open to all suggestions to make it more accessible. Using branches for starting points and intermediate results is not really self-explanatory, so there will be an appendix on how we thought it should work.